1. FIELD OF THE INVENTION
The invention relates generally to a device for centering a target in the beam of a particle accelerator, without violating the restrictions of sliding friction within the ultra high vacuum atmosphere.
2. DESCRIPTION OF THE PRIOR ART
Linear actuators currently in use employ a system that manipulates the entire drive mechanism outside the vacuum to locate the target in the desired position within the particle beam. Reaching through the vacuum bellows to the center of the beam tube, results in a target support member that has an eleven inch moment arm supported by a two and a half inch reaction. During the "bakeout period" the entire drive mechanism is subjected to elevated temperatures, and the resultant stresses of the heater blanket. The difficult positioning mechanism is exposed to tampering, which would cause the device to be removed, and reset. The drive mechanism cannot be removed without breaking the vacuum seal. Since the drive mechanism moves independently of the accelerator, flexible air hoses are required which are exposed to damage. The shaft, guide device, bellows, and pneumatic cylinder are on the same centerline, resulting in height that is not feasible for certain applications. Mounting the "tilt" baseplates for the drive mechanism requires an oversized custom vacuum flange, which covered by the tilt flanges, provides difficult access to the vacuum flange face, and electrical input ports. This invention eliminates all of these encumbrances.